Generally, a fuel supply device consisting of a fuel tank in which fuel is stored, a fuel pump disposed in the fuel tank to discharge the fuel in the fuel tank to the exterior thereof, and a fuel filter provided in the fuel tank together with the fuel pump to purify the fuel discharged from the fuel pump, is well known.
In this sort of conventional fuel supply device, in order to feed the fuel in the fuel tank within toward the engine, the fuel pump and the fuel filter are disposed in the fuel tank under a condition where the fuel pump and the fuel filter are integrally installed on a mounting bracket made of synthetic resin, and contacts the fuel, such as gasoline, stored in the fuel tank.
During operation of the engine, the fuel within the fuel tank is discharged by means of the fuel pump, and flows through the fuel filter for purification, and then fed into the outside of the fuel tank toward each of fuel injection valves of the engine.
On the other hand, the fuel filter is constructed by a filter case installed on the mounting bracket, and a filter element disposed in the filter case. A fuel flow passageway is defined between the filter case and the filter element. The fuel, discharged out of the fuel pump and entering into the fuel filter, is purified by way of the filter element, while flowing through the above-mentioned flow passageway.
In the previously-noted prior art, the fuel, which is discharged from the fuel pump during operation of the engine, enters into the fuel filter, and passes through the filter element of fine mesh. Thus, there is a tendency turbulent flow to occur within the fuel filter, since the fuel flow is violently disturbed just before and after the filter element. As a result, static electricity builds up in the filter case of the fuel filter due to the filter case put into contact with the fuel.
However, for the purpose of compactly disposing the filter case in the fuel tank, the filter case is installed on the mounting bracket made of synthetic resin together with the fuel pump, so that the filter case is kept in an electrically insulated state within the fuel tank.
For the reasons set forth above, the prior art has a problem that the static electricity charged in the filter case due to friction between the filter case and the fuel is gradually stored and built up.